Eosinophils are white blood cells of the granulocytic lineage. Their normal functions include combating parasitic infections, particularly helminthic infections. See, e.g., Janeway, et al. (eds. 1996) Immunobiology: The Immune System in Health and Disease 2nd Ed., Garland Publishing, New York, N.Y.; and Rich (ed. 1996) Clinical Immunology: Principles and Practice Mosby, St. Louis, Mo. However, their accumulation in tissues, a condition referred to as eosinophilia, is also associated with several abnormal or disease states, including hypereosinophilia, chronic pneumonia, allergic bronchopulmonary aspergillosis, Churg-Strauss Syndrome, atopic dermatitis, and most notably asthma. See, e.g., Frigas, et al. (1986) J. Allergy Clin. Immunol. 77:527-537; Weller (1984) J. Allergy Clin. Immunol. 73:1-10; and Frank, et al. (eds. 1995) Samter's Immunological Diseases 5th Ed., vol. I-II, Little, Brown, and Co., Boston, Mass.
Currently glucocorticoid steroids are the preferred therapeutic drugs for treating the acute effects of allergic diseases, such as asthma. However, prolonged steroid treatment is associated with many deleterious side effects. See, e.g., Goodman and Gilman (eds.) The Pharmacological Basis of Therapeutics MacMillan Publishing Company, New York, N.Y. Moreover, the steroids apparently do not affect the production or accumulation of granulocytic cells, such as eosinophils, in the afflicted tissues. Such leads to treatment of symptoms rather than the underlying cause.
More recently, it has been shown that eosinophilia associated with certain immune disorders could be treated by the administration of an antagonist to interleukin-5 (IL-5). See, e.g., Coffman, et al. (1989) Science 245:308-310; and Coffman, et al. U.S. Pat. No. 5,096,704. IL-5 is a potent eosinophil differentiation factor, but also exerts effects on other immune cells, e.g., B cells. However, this antagonist can affect other cell types besides eosinophils.
The availability of alternative or complementary approaches to the treatment of disorders associated with eosinophilia would have important clinical utility. Preventing the production or accumulation of eosinophils in the relevant tissues may block the underlying cause of these disorders or diseases.